Anode foils for electrolytic capacitors and methods for making same

Abstract

Anode foils suitable for use in electrolytic capacitors, including those having multiple anode configurations, have improved strength, reduced brittleness, and increased capacitance compared to conventional anode foils for electrolytic capacitors. Exemplary methods of manufacturing an anode foil suitable for use in an electrolytic capacitor include disposing a resist material in a predetermined pattern on an exposed surface of an anode foil substrate such that a first portion of the exposed surface of the anode foil substrate is covered by the resist material, and a second portion of the exposed surface remains uncovered; polymerizing the resist material; exposing at least the second portion of the exposed surface to one or more etchants so as to form a plurality of tunnels; stripping the polymerized resist material; and widening at least a portion of the plurality of tunnels. The resist material may be deposited, for example, by ink-jet printing, stamping or screen printing.

What is claimed is: 
     
       1. A method of manufacturing an anode foil suitable for use in an electrolytic capacitor, comprising:
 disposing a resist material in a predetermined pattern on an exposed surface of a continuous web of anode foil substrate, such that a first portion of the exposed surface of the anode foil substrate is covered by the resist material, and a second portion of the exposed surface is uncovered; 
 polymerizing the resist material; 
 exposing at least the second portion of the exposed surface to one or more etchants to form a plurality of tunnels; 
 thermally stripping the polymerized resist material using gas temperatures above 200° C. and below a melting point of the anode foil; and 
 widening at least a portion of the plurality of tunnels. 
 
     
     
       2. The method of  claim 1 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by ink-jet printing. 
     
     
       3. The method of  claim 1 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by stamping. 
     
     
       4. The method of  claim 1 , wherein the resist material comprises acrylic monomers and ultraviolet photo initiators. 
     
     
       5. The method of  claim 1 , wherein the resist material is a liquid comprising acrylic monomers and ultraviolet photo initiators. 
     
     
       6. The method of  claim 1 , wherein thermally stripping the polymerized resist material comprises forced air drying and baking at a temperature sufficient to break down and oxidize the polymerized resist material. 
     
     
       7. The method of  claim 1 , wherein widening comprises exposing the etched anode substrate to polystyrenesulfonic acid. 
     
     
       8. The method of  claim 7 , further comprising a step after the widening step of hydrating the etched substrate. 
     
     
       9. The method of  claim 7 , further comprising a step after the stripping step of vaporizing residue disposed on the etched anode substrate. 
     
     
       10. The method of  claim 7 , further comprising:
 heat treating the anode foil to remove residue; and 
 forming an oxide layer on the etched anode substrate. 
 
     
     
       11. A method of manufacturing an anode foil suitable for use in an electrolytic capacitor, comprising:
 disposing a resist material in a predetermined pattern on an exposed surface of a continuous web of anode foil substrate, such that a first portion of the exposed surface of the anode foil substrate is covered by the resist material, and a second portion of the exposed surface remains exposed; 
 polymerizing the resist material; 
 exposing the second portion of the exposed surface to at least one etchant to form a plurality of etched areas; 
 thermally stripping the polymerized resist material by heating the anode foil substrate to a temperature above 200° C. and maintaining the temperature less than the melting point of the anode foil substrate; and 
 widening at least a portion of the etched areas. 
 
     
     
       12. The method of  claim 11 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by ink-jet printing. 
     
     
       13. The method of  claim 11 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by stamping. 
     
     
       14. The method of  claim 11 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by screen printing. 
     
     
       15. The method of  claim 11 , wherein the resist material comprises acrylic monomers and ultraviolet photo initiators. 
     
     
       16. A method of manufacturing an anode foil suitable for use in an electrolytic capacitor, comprising:
 disposing a resist material in a predetermined pattern on a first portion of a surface of a continuous web of anode foil substrate that has edges, such that a second portion of the surface of the anode foil substrate is not covered by the resist material, wherein the first portion includes a frame on the edges of the anode foil substrate; 
 polymerizing the resist material; 
 exposing the second portion of the anode foil substrate to one or more etchants to form a plurality of tunnels; 
 thermally stripping the polymerized resist material at a gas temperature above 200° C. and below a melting point of the anode foil; and 
 widening at least a portion of the plurality of tunnels. 
 
     
     
       17. The method of  claim 16 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by ink-jet printing. 
     
     
       18. The method of  claim 16 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by stamping. 
     
     
       19. The method of  claim 16 , wherein disposing the resist material in a predetermined pattern comprises applying the resist material by screen printing. 
     
     
       20. The method of  claim 16 , wherein the resist material comprises acrylic monomers and ultraviolet photo initiators.